True. The number of engineers is not linearly correlated with the number of customers, but the number of features. If you have a relatively simple product and you can somehow still compete (niche market, patents etc), you can get away with a very low head count. WhatsApp famously had only 35 engineers and ~450M users when Facebook acquired them.
> which is probably what happened to them inside facebook anyways
I think initially they only expanded to ~50 engineers until 900M users. Even today they are estimated to have only ~500 employees (no idea what percentage of that are engineers).
LinkedIn lists 1823 people working at Whatsapp, not sure how accurate that number is, probably self-reported so could be lower/higher, but ~500 seems off. Employee count seems to grow 1-5% month-to-month.
Engineering is listed as 25% of those 1823, operations 8%, education 6% and business development 6%.
